This invention relates to a frame construction for a motorcycle and more particularly to an improved, lightweight, high strength frame.
The desirability of maintaining lightweight for motorcycles has well as a low center of gravity is well known. Of course, in addition to maintaining a lightweight the motorcycle and particularly its frame construction must be extremely strong so as to resist the loads encountered when operating a motorcycle. One type of frame construction which is receiving considerable attention is that of the "Delta Box" type. With this type of frame, a pair of box shaped fabricated main frame members extend downwardly and rearwardly in almost a straight line from the head pipe to a pivot point for the rear wheel suspension. This type of frame construction has many of the desirable advantages called for in frame constructions. However, certain types of motorcycle application, such as moto-crossing, place abnormally high loads on the frame, particularly from the front wheel.
It is, therefore a principal object to this invention to provide an improved lightweight,. high strength frame for a motorcycle.
It is further object to this invention to provide a motorcycle frame of the type known generally as a "Delta Box" frame wherein the frame is reinforced against loads encountered by the front wheel in application such as moto-crossing.
It is a further object to this invention to provide an improved, lightweight, compact and neat appearing frame construction for a motorcycle.
One way in which the frame construction can be reinforced is by providing a center main frame member which is affixed to the head pipe at its forward end and is affixed to the pair of main frame members at a point spaced therefrom by a cross member assemblage. However, previous constructions of this type have placed the center main frame member at the same angle as the pair of side main frame members and hence have not fully triangulated and strengthen the construction. In addition, the center main frame member has been attached to the head pipe previously a point above the side main frame members and thus results in a triangular configuration when viewed in transversed cross sections which does not permit maximum space utilization and also which provides an uncomfortable seating arrangement.
It is, therefore, a still further object to this invention to provide an improved frame assembly for a motorcycle having a center main frame member and a pair of side main frame members that has a good overall configuration and high strength due to triangulation of the construction.